Patent GB-269043-A (GB)
Title: Improvements in and relating to stopping means adapted to talking machines
IPC: G11B17/02
Filed: 1926-08-23
Abstract: 269,043. Waterworth, E. N. Aug. 23, 1926. Stopping.-Relates to gramophones in which a brake is applied automatically by mechanism brought into action by the cessation of movement of the tone-arm, and consists of detail improvements in apparatus of the type in which, during the operation of the machine, an oscillatory member is moved periodically by mechanism driven by the machine motor into such a position that unless it is shortly afterwards withdrawn by the action of the moving tone-arm, it subsequently brings into action mechanism for applying the brake. When the machine is running, a brake-lever 42 is held by a cam 36 on a lever 38 so that a friction pad 45 is clear of the rim of the turntable. A pawl 34 lies adjacent to but free from the cam 36, the pawl being mounted on a plate 17 which is freely mounted on the turntable spindle 13, but is normally held in the position shown by a spring 20. The plate has pivoted thereon a wheel 15 gearing with a pinion 14 on the spindle 13. The wheel 15 carries on opposite faces two pins 18, 19, the pin 18 brushing past an inclined projection 32 on a bell-crank lever 30 which is pivoted on a lever 24, and is normally held as shown by a strong spring 31. On each revolution of the wheel 15, the action of the pin 18 on the lever 30 rocks the lever 24 about its pivot 27, but when the tone-arm is moving, the lever is restored to its normal position, shown in the drawing, as soon as the pin 18 has passed the lug 32. This reverse movement of the lever 24 is effected by a curved arm 12, which is slowly advanced by means of a member moving with the tone-arm, the arm 12 having a knurled surface engaging with a knife-edge 26 connected to the lever 24 by a blade spring 25. A lever 22 is pivoted at 23, one arm of the lever lying under the wheel 15, and the other arm passing under the lever 24 and having a turned-up end engaging the spring 25. The function of the lever 22 is to disengage the member 26 from contact with the arm 12 whilst the lever 24 is being rocked by the action of the pin 18, so as to avoid the imposition of strain, on the mechanism connected with the tone-arm, and consequent injury to the record. This temporary disengagement is effected by means of the pin 19 on the underside of the wheel 15, which pin engages the lever 22 before the pin 18 operates, and causes the upturned end of the lever 22 to press the spring 25 away from the arm 12. A spring 29, acting through a lever 28 engaging with the lever 24 tends to hold the lever 24 in the position shown, but this spring is out of action when, after the tone-arm has travelled partly across the record, the arm 12 is advanced and turns the lever 28. The application of the brake is finally effected as follows. When the tonearm stops and the lever 24 is consequently left in the position into which it has been moved by the pin 18, the next revolution of the wheel 15 causes the pin to engage in a tooth 33 in the lever 30. This arrests the wheel 15, whereupon movement of that plate 17 around the spindle 13 occurs. This causes the pawl 34 to engage and turn the quadrant 36, thus freeing the brake-lever 42. Where an electric motor is employed for driving the machine, the circuit is controlled by a switch operated by the brake mechanism.